Distance covered by truck in 1 minute = 550 m = $$frac{550}{1000}=frac{11}{20}$$ km Time taken by bus = $$frac{3}{4} imes 60=45$$ minutes Distance covered by bus in 45 minutes = 33 km Thus, distance covered in 1 minute = $$frac{33}{45}=frac{11}{15}$$ km $$ herefore$$ Ratio of speeds of trucks and bus = $$frac{11}{20} div frac{11}{15}$$ = $$frac{11}{20} imes frac{15}{11}=frac{15}{20}$$ = $$frac{3}{4}$$ = 3 : 4 => Ans - (C)